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Understanding wind-solar hybrid systems

September 30, 2010
Bychris

If you’re interested in renewable energy, you’ve probably heard the term wind-solar hybrid before and wondered what that really meant. On the surface, it's pretty straight forward; it’s a renewable energy system, generally small, designed to provide power for your home or small business.

But there’s a difficult side to this technology: How do you connect two or more different types of electric current, condition, and convert it into usable, stable electricity for your home or building? And why consider a hybrid system anyhow?

You want to consider a hybrid system when you’re off-grid or if you’re just a diehard fan of renewable energy with a fair amount of money to spend. When homes are more than a mile off the grid, costs of running power lines to a home start to become more expensive ($15,000 to $50,000 per mile) and quickly eclipse the price of installing a solar or hybrid system, and its backup, usually a battery bank or a generator. Altogether a small hybrid system and its installation will likely cost upwards of $20,000—but could be significantly more.

Traditionally, these systems have included separate wind turbines and solar arrays tied together at a controller, but some newer systems incorporate both into one installation in an attempt to reduce complexity and the system’s overall footprint.

Since hybrid systems include both solar and wind power, they allow the power user to benefit from the advantages provided of both forms of energy. Obviously, solar panels don’t provide power during the night, but that’s when the wind usually picks up and conversely, on the longest, hottest days of days of summer, the wind often doesn’t blow, but the sun is at its strongest—great for solar power. The wind is more likely to blow during the cold, short days of winter when the sun is at its weakest.

Between the two generation methods, they offer a more comprehensive alternative to grid-powered electricity. However, there is still the matter of what to do when neither are working, aka energy storage. This can be done by tying the system to the grid, by using a battery bank (usually designed to store three days worth of the users’ power needs) or a backup generator.

Adding a second and a third power supply to a system adds both cost and complexity to a somewhat already complex system, but special electric controllers are designed to integrate all three (the DC power from the solar array, the AC/DC or three-phase AC from the wind turbine, and the power from the backup). The power controller will integrate the wind, solar, and backup system providing power to the user, and send additional power to a battery bank or the grid, giving the user a reliable, stable source of energy.